1. Field of the Invention
The present invention relates generally to a water purification system, and in particular to a two-stage reverse-osmosis filtering process utilizing a carbon block pre-filter.
2. Discussion of the Related Art
Reverse osmosis units have been used for many years to purify water for residential, municipal, and industrial uses. Some systems are self-contained and are generally designed to provide potable water on demand by being connected to a municipal water supply line. These systems create a ready reservoir of purified or potable water which would be available to be dispensed to a user, either by gravity flow or by flow driven by the expansion of air compressed behind a bladder within a confined tank. Other systems are designed to rest on the countertop or attach directly to a water faucet.
Reverse-osmosis membrane separation devices generally function on the basis of employing a significant fluid pressure difference between the inlet side of the membrane barrier, often referred to as the feed side, and the opposite side of the membrane barrier, which is known as the product side. This pressure difference motivates the flow of fluid through the micropores of the membrane barrier while generally preventing the passage of salt and mineral solutes through the membrane. In some small scale or domestic appliance-type membrane separation systems, a liquid accumulation reservoir or tank is provided into which the desired permeate discharge from the membrane purification unit is directed. Such a tank provides for rapid dispensing of a fairly large quantity of product liquid at the tap or other point of use. Moreover, because the tank or reservoir can be repeatedly filled to its desired capacity during periods of water non-use, this arrangement permits the use of a small, economical membrane separation device having only a relatively low, direct, product flow rate. Various systems have been developed to increase the efficiency and effectiveness of reverse osmosis units, but the search for improvement is continuing.